Methods and apparatus to heat liquids in dishwashers

ABSTRACT

Methods and apparatus to heat liquids in dishwashers are disclosed. An example dishwasher includes a tub defining at least partially a treating chamber for treating dishes according to an automatic cycle of operation, at least two sprayers located in the treating chamber for spraying liquid into the treating chamber and a diverter assembly. An example diverter assembly includes a diverter chamber, a diverter configured to sequentially divert the liquid from the diverter chamber to the at least two sprayers, and a heater located within the diverter chamber and configured to heat the liquid as it passes through the diverter chamber.

FIELD OF THE DISCLOSURE

This disclosure relates generally to dishwashers, and, more particularly, to methods and apparatus to heat liquids in dishwashers.

BACKGROUND

A dishwasher is a domestic appliance into which dishes and other cooking and eating wares (e.g. plates, bowls, glasses, flatware, pots, pans, bowls, etc.) are placed to be washed. The dishwasher may include a heater to heat liquid circulated onto the dishes. Conventional dishwashers heat liquids using a heating element at the bottom of the tub.

SUMMARY

Methods and apparatus to heat liquids in dishwashers are disclosed. In a first aspect, an example dishwasher includes a tub defining at least partially a treating chamber for treating dishes according to an automatic cycle of operation, at least two sprayers located in the treating chamber for spraying liquid into the treating chamber, and a diverter assembly. An example diverter assembly includes a diverter chamber, a diverter configured to sequentially divert the liquid from the diverter chamber to the at least two sprayers, and a heater located within the diverter chamber and configured to heat the liquid as it passes through the diverter chamber.

In a second aspect, an example dishwasher includes a tub defining at least partially a treating chamber for treating dishes according to an automatic cycle of operation, at least two sprayers located in the treating chamber for spraying liquid into the treating chamber; and a diverter assembly. The diverter assembly includes a diverter chamber; a bottom plate that defines a channel; a diverter configured to sequentially divert the liquid from the diverter chamber to the at least two sprayers; and a heater located within the diverter chamber. The heater is received in at least a portion of the channel and configured to heat the liquid as it passes through the diverter chamber.

In another aspect, an example method for heating water in a dishwasher is disclosed. The dishwasher has a tub defining at least partially a treating chamber for treating dishes according to an automatic cycle of operation, and at least two sprayers located in the treating chamber for spraying liquid into the treating chamber. The method includes directing a liquid from a sump into a diverter chamber, heating the liquid in the diverter chamber, and sequentially diverting the heated liquid from the diverter chamber to the sprayers.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic, side cross-sectional view of a dishwasher according to a first embodiment of the invention.

FIG. 2 is a schematic view of a controller of the dishwasher of FIG. 1.

FIG. 3 is a bottom isometric view of sump and diverter assembly of the dishwasher of FIG. 1.

FIG. 4 is a perspective view of the sump and diverter assembly of the dishwasher of FIG. 1 with portions cut away for clarity.

FIG. 5 is a bottom isometric view of an example manner of implementing the heater of FIGS. 3 and 4.

FIG. 6 is a bottom isometric view of an alternate example manner of implementing the heater of FIGS. 3 and 4.

DETAILED DESCRIPTION

The invention may be implemented in any environment using a diverter and a pump assembly for heating and transferring liquid. While the illustrated diverter and pump assembly has particular utility in a dishwashing machine, the diverter and pump assembly may also be applicable to any appliance configured to use heated liquid.

In FIGS. 1 and 2, an automated dishwasher 10 according to a disclosed embodiment is illustrated. The dishwasher 10 shares many features of a conventional automated dishwasher, which will not be described in detail herein except as necessary for a complete understanding of this disclosure. A chassis or frame 12 may define an interior of the dishwasher 10 and may include a frame, with or without panels mounted to the frame. An open-faced tub 14 may be provided within the chassis 12 and may at least partially define a treating chamber 16, having an open face, for washing dishes. A door 18 may be movably (e.g., rotationally) mounted to the dishwasher 10 for movement between opened and closed positions to selectively open and close the open face of the tub 14. Thus, the door 18 provides accessibility to the treating chamber 16 for the loading and unloading of dishes or other washable items. While not shown in FIG. 1, the door 18 may include a consumable dispenser (not shown). Alternatively, the consumable dispenser may be located elsewhere in the dishwasher 10.

It should be appreciated that the door 18 may be secured to the lower front edge of the chassis 12 or to the lower front edge of the tub 14 via a hinge assembly (not shown) configured to pivot the door 18. When the door 18 is closed, user access to the treating chamber 16 may be prevented, whereas user access to the treating chamber 16 may be permitted when the door 18 is open.

Dish holders, illustrated in the form of upper and lower dish racks 26, 28, are located within the treating chamber 16 and receive dishes or other items for washing and/or drying. The upper and lower racks 26, 28 may be mounted to dish rack mounts (not shown) via disk rack rails (not shown) for slidable movement in and out of the treating chamber 16 for ease of loading and unloading. Other dish holders may be provided, such as a silverware basket. As used in this disclosure, the term “dish(es)” is intended to be generic to any item, single or plural, that may be treated in the dishwasher 10, including, without limitation, dishes, plates, pots, bowls, pans, glassware, utensils, and silverware.

A spray system is provided for spraying liquid in the treating chamber 16 and is provided in the form of a first lower spray assembly 34, a second lower spray assembly 36, a rotating mid-level spray arm assembly 38, and/or an upper spray arm assembly 40. Upper sprayer 40, mid-level rotatable sprayer 38 and lower rotatable sprayer 34 are located, respectively, above the upper rack 26, beneath the upper rack 26, and beneath the lower rack 28 and are illustrated as rotating spray arms. The second lower spray assembly 36 is illustrated as being located adjacent the lower dish rack 28 toward the rear of the treating chamber 16. The second lower spray assembly 36 is illustrated as including a vertically oriented distribution header or spray manifold 44. Such a spray manifold is set forth in detail in U.S. Pat. No. 7,594,513, issued Sep. 29, 2009, and titled “Multiple Wash Zone Dishwasher,” which is incorporated herein by reference in its entirety.

A recirculation system is provided for recirculating liquid from the treating chamber 16 to the spray system. The recirculation system comprises a sump assembly 29, which may include a sump 30 and a pump assembly 31. The sump 30 collects the liquid sprayed in the treating chamber 16 and may be formed in part or whole by a sloped or recess portion of a bottom wall of the tub 14. The pump assembly 31 may include both a drain pump 32 and a recirculation pump 33. The drain pump 32 may draw liquid from the sump 30 and pump the liquid out of the dishwasher 10 to a household drain line (not shown). The recirculation pump 33 may draw liquid from the sump 30 and the liquid may be simultaneously or selectively pumped through a diverter assembly 41 and/or recirculation circuits 42 to each of the spray assemblies 34, 36, 38, 40 for selective spraying. While not shown, a liquid supply system may include a water supply conduit coupled with a household water supply for supplying water to the treating chamber 16.

A heating system including a heater 305 (FIGS. 3 and 4) is located in the diverter assembly 41 for heating liquid flowing from the sump 30 to the spray arm assemblies 34, 36, 38 and 40 via the recirculation pump 33 and the diverter assembly 41.

The controller 50 is operably coupled with various components of the dishwasher 10 to implement a cycle of operation. The controller 50 may be located within the door 18 as illustrated, or it may alternatively be located somewhere within the chassis 12. The controller 50 may also be operably coupled with a control panel or user interface 56 for receiving user-selected inputs and communicating information to the user. The user interface 56 may include operational controls such as dials, lights, switches, and displays enabling a user to input commands, such as a cycle of operation, to the controller 50 and receive information. In some examples, the controller 50 and the user interface 56 may be implemented in a crown of the door 18 that forms the top portion of the door. Generally, the crown of the door is attached to front and rear panels of the door during assembly/manufacture.

As illustrated schematically in FIG. 2, the controller 50 may be coupled with the heater 305 for heating the wash liquid during a cycle of operation, the drain pump 32 for draining liquid from the treating chamber 16, and the recirculation pump 33 for recirculating the wash liquid during the cycle of operation. The controller 50 may be provided with a memory 52 and a central processing unit (CPU) 54. The memory 52 may be used for storing control software and/or machine-readable instructions that may be executed by the CPU 54 in completing a cycle of operation using the dishwasher 10 and any additional software. For example, the memory 52 may store one or more pre-programmed cycles of operation that may be selected by a user and completed by the dishwasher 10. The controller 50 may also receive input from one or more sensors 58. Non-limiting examples of sensors that may be communicably coupled with the controller 50 include a temperature sensor, and a turbidity sensor to determine the soil load associated with a selected grouping of dishes, such as the dishes associated with a particular area of the treating chamber.

In FIGS. 3-5, an example sump assembly 29 according to a disclosed embodiment is illustrated. As shown, the drain pump 32 and the recirculation pump 33 are fluidly coupled to the sump 30. Liquid is directed into the diverter assembly 41 via a conduit 310. As best shown in FIG. 4, the conduit 310 delivers liquid though a side of the diverter 41 into a diverter chamber 405. The bottom-plate forming the bottom portion 420 of the diverter assembly 41 has a projection 422 that projects into the diverter chamber 405 and extends upward to locate the heater 305 along the bottom of the diverter chamber 405 adjacent the liquid that passes there through. The bottom portion 420 at least partially defines a continuous annular groove, for example a channel 425, in which a heating element 430 may be at least partially received to heat liquid that passes through the diverter chamber 405. At least a portion of the channel 425 may be at least twice as wide as the heating element 430.

A dually wound heating element 430 is shown positioned within the channel 425 such that the heating element 430 contains more than one cross sectional segment within a cross sectional plane in at least a portion of the channel 425. As shown, rotational segments of the dually wound heating element 430 are separated by at least a gap 435. Alternative patterns of positioning a heating element 430 within at least a portion of the channel 425 are envisioned. For example, the heating element 430 may have more than two windings, a zig-zag winding (i.e., in short, radially inward and outward segments), or multiple concentric coils within the channel 425. In another example, dual heating elements may be configured to encircle the channel 425 in a similar dual-winding pattern. In yet another example, a single heating element may be configured in more than one winding pattern.

As best shown in FIG. 5, the heating element 430 further includes terminating end caps 515 that may be used to electrically couple the element 430 with the energizable power source (not shown). Alternative methods of heat supply and corresponding end caps are envisioned.

The channel 425 may further include a plurality of convolutions 440 extending from a portion of the bottom portion 420 into the diverter chamber 405. In the illustrated example, the convolutions 440 include peaks 442 and valleys 444, with at least a portion of the peaks 442 extending away from the heating element 430 such that the peaks 442 are not in direct contact with the heating element 430. The valleys 444 may define at least a portion of a heater seat 446 which abuts the heating element 430 such that the valleys 444 and the heating element 430 are thermally coupled. The space between the heating element 430 and the peaks 442 may additionally be filled with an optional filling material, such as a thermally conductive brazing material (not shown), wherein the filling may include a portion of the heater seat 446. While not illustrated, a brazing material may fill the gap 435 between the heating element 430 segments. Alternatively, the heating element 430 may not be physically received by the heater seat 446 so long as the element 430 may be proximately located to provide for heat transference from the element 430 to the projection 422.

While the convolutions 440 are only shown on one side of the channel 425, the convolutions 440 may be provided on any portion of the bottom portion 420 in fluid contact with the diverter chamber 405. Additionally, in embodiments where the projection 422 may have an alternate cross sectional shape, which may not have well-defined sides, it is envisioned at least a portion of the projection 422 may have the convolutions 440.

The configuration of the heating element 430 and convolutions 440 defines a heat transfer area (not shown) operably increasing the surface area of the heater seat 446 that is in conductive contact with the diverter chamber 405, which in turn increases the rate at which heat is transferred to the liquid. The increased rate of heat transfer to the liquid is provided without increasing the corresponding size of the heating element 430. The filling of the peaks 442 with brazing material further enhances the conductive transfer as heat is conducted to the convolutions 440, where otherwise the heat would first transfer by convection with the air in the peaks 442 before conduction to the liquid.

The depth 450 to which the projection 422 may extend into the diverter chamber 405 may vary. As illustrated, the depth 450 can be more or less, and can even include a depth greater than the height of the heating element 430. While the depth 450 is illustrated as more than half the height of the heating element 430, the amount of cross sectional area of the heating element in contact with the heater seat 446 is less than fifty percent, a greater or lesser amount of the surface of the heating element may be in contact with the heater seat.

In operation, wash liquid, such as water and/or treating chemistry (i.e., water and/or detergents, enzymes, surfactants, and other cleaning or conditioning chemistry), enters the tub 14 and flows into the sump 30 to the diverter assembly 41 via a conduit 310. The conduit 310 delivers liquid though the side of the diverter 41 into the diverter chamber 405. As liquid flows through the diverter chamber 405, it passes through the peaks 442 and valleys 444 of the convolutions, which provide an increased surface area, and consequently, an increased heat transfer area 450 and enhanced rate of conduction, as compared to a flat surface.

While liquid is being recirculated within the dishwasher 10, a power or heating source may selectively energize the heater 305, causing the heater 305 to generate heat. The heat generated by the heater 305 may be thermally conducted through the channel 425, the heater seat 446, brazing material (if present), convolutions 440, and any non-convoluted sides of the channel 425 to heat the liquid as it passes through the diverter chamber 405. The liquid then flows out the top of the diverter chamber 405 through a disc or diverter 410 and is directed to at least one of the lower rotatable sprayer 34, mid-level rotatable sprayer 38, upper sprayer 40, and spray manifold 44.

To direct the heated liquid to ones of the spray assemblies 34, 36, 38 and 40, the disc or diverter 410 is rotated by a diverter motor 315 via a shaft 415. The disc or diverter 410 has a hole that permits liquid to flow through the diverter 410. As the diverter 410 is rotated by the diverter motor 315 liquid is sequentially directed to the spray arm assemblies 34, 36, 38 and 40.

In some examples (e.g., see FIG. 5), the heater 305 comprises one or more tubular electric heaters 505 and 510, such as a calrod, however, many different heating elements may be acceptable in embodiments of the current invention including, but not limited to, a thick film plate heater.

In other embodiments, it is contemplated that the heater is a calrod heater assembly 630 that protrudes into the diverter chamber 405 as shown in FIG. 6.

The embodiments disclosed herein provide a diverter assembly for a dishwasher. Calcium precipitates out of water at higher temperatures, creating water scale at or near the heating element. One advantage that may be realized in the above embodiments is that the above described embodiments allow for an elongated heating element surface area, and thus generating heat over a larger heat transfer area. This operatively reduces the watt density of the heat transfer area by distributing a known wattage over a longer length, which in turn, reduces calcium precipitation while heating the liquid. Another advantage of the above embodiments may be that the effective heat transfer from the heating element to the liquid may be further increased using the optional heat-transferring brazing material. Yet another advantage of the above embodiments may be that the increased heat transfer surface area of the plurality of convolutions 440 further increases the effective heat transfer of the heating element and brazing material, and further reduces the watt density of the heating element. Even yet another advantage of the above embodiments may be that any calcium or water scale that does develop at the heat transfer area will harden and break off during the thermal expansion and contraction at the convex surfaces of the peaks and valleys of the convolutions. In another advantage of the above described embodiments, the projection's depth into the diverter chamber increases the heat transfer area, further reducing the watt density of the heating element

To the extent not already described, the different features and structures of the various embodiments may be used in combination with each other as desired. That one feature may not be illustrated in all of the embodiments may be not meant to be construed that it may not be, but may be done for brevity of description. Thus, the various features of the different embodiments may be mixed and matched as desired to form new embodiments, whether or not the new embodiments are expressly described. All combinations or permutations of features described herein are covered by this disclosure. The primary differences among the exemplary embodiments relate to a diverter assembly, and these features may be combined in any suitable manner to modify the above described embodiments and create other embodiments.

This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims. 

1. A dishwasher comprising: a tub defining at least partially a treating chamber for treating dishes according to an automatic cycle of operation; at least two sprayers located in the treating chamber for spraying liquid into the treating chamber; and a diverter assembly including: a diverter chamber; a diverter configured to sequentially divert the liquid from the diverter chamber to the at least two sprayers; and a heater located within the diverter chamber and configured to heat the liquid as it passes through the diverter chamber.
 2. The dishwasher of claim 1, wherein the heater comprises an electric tubular heater.
 3. The dishwasher of claim 1, wherein the heater comprises a calrod heater.
 4. The dishwasher of claim 1, wherein the heater comprises multiple concentric coils.
 5. The dishwasher of claim 1, wherein the diverter assembly further includes a bottom plate and the heater extends through the bottom plate into the diverter chamber.
 6. The dishwasher of claim 1, wherein the diverter assembly further comprises: a shaft passing through the diverter chamber; a disc as the diverter fixedly affixed to the shaft above the diverter chamber, the disc having an opening; and a motor to rotate the shaft thereby sequentially directing the liquid from the diverter chamber to the sprayers.
 7. The dishwasher of claim 1, further comprising: a sump; and a recirculation pump to direct the liquid from the sump to the diverter chamber.
 8. A The dishwasher of claim 7, wherein the heater comprises an electric tubular heater situated at a bottom of the diverter chamber, and wherein the recirculation pump directs the liquid into the diverter chamber above the electric tubular heater.
 9. The dishwasher of claim 7, further comprising a sump assembly comprising: the diverter assembly; the sump; and the recirculation pump.
 10. A dishwasher comprising: a tub defining at least partially a treating chamber for treating dishes according to an automatic cycle of operation; at least two sprayers located in the treating chamber for spraying liquid into the treating chamber; and a diverter assembly including: a diverter chamber; a bottom plate that defines a channel; a diverter configured to sequentially divert the liquid from the diverter chamber to the at least two sprayers; and a heater located within the diverter chamber, the heater received in at least a portion of the channel and configured to heat the liquid as it passes through the diverter chamber.
 11. The dishwasher of claim 10, wherein the channel further comprises convolutions extending from a portion of the bottom plate into the diverter chamber.
 12. The dishwasher of claim 11, wherein the convolutions comprise peaks and valleys.
 13. The dishwasher of claim 12, wherein the valleys define at least a portion of a heater seat on which at least a portion of the heater rests.
 14. The dishwasher of claim 10, wherein the channel conforms to the shape of the heater.
 15. The dishwasher of claim 10, wherein the heater comprises multiple concentric coils.
 16. A method for heating water in a dishwasher having a tub defining at least partially a treating chamber for treating dishes according to an automatic cycle of operation, and at least two sprayers located in the treating chamber for spraying liquid into the treating chamber, the method comprising: directing a liquid from a sump into a diverter chamber; heating the liquid in the diverter chamber; and sequentially diverting the heated liquid from the diverter chamber to the sprayers.
 17. The method of claim 16, further comprising heating the liquid with an electric tubular heater.
 18. The method of claim 16, further comprising heating the liquid with a calrod heater.
 19. The method of claim 16, further comprising diverting the heated liquid from the diverter chamber to the sprayers via respective recirculation circuits.
 20. The method of claim 16, further comprising: heating the liquid with an electric tubular heater situated at a bottom of the diverter chamber; directing the liquid into the diverter chamber at a side of the diverter chamber above the electric tubular heater; and diverting the heated liquid from the diverter chamber to the sprayers via a top of the diverter chamber. 